It is known that 2-pyridone compounds can be produced by making 3-oxobutanamide react with a various kind of ketone compound. Specifically, 4,6-dimethyl-2-pyridone is obtained by making 3-oxobutanamide react with acetone in the presence of polyphosphoric acid; 3-acetyl-4,6-dimethyl-2-pyridone is obtained by making 3-oxobutanamide react with pentan-2,4-dione in the presence of hydrogen chloride or polyphosphoric acid; and 5-ethoxycarbonyl-4,6-dimethyl-2-pyridone is obtained by making 3-oxobutanamide react with ethyl acetoacetate in the presence of polyphosphoric acid (Chem. Pharm. Bull. 28(7) 2244–2247 (1980). J. Chem. Soc. (C), 1967, 1836–1839).
